BOSTON -- Kelly Olynyk will readily tell you what a difference a healthy pair of ankles makes.

In his best performance since missing 10 games due to a severe ankle sprain, Olynyk finished with a team-high 21 points and five assists, including 10 big points in the fourth quarter as the Celtics traded blows with the Hawks before falling, 92-91.

"I definitely felt more comfortable," Olynyk said. "I was moving better. I felt more fluid. I'm getting back to how I was feeling before."

Olynyk had averaged just 3.7 points, 3.5 rebounds and 1.3 assists in about 13 minutes per games in the six games he played coming into Tuesday after returning from injury. On New Year's Eve, he looked like he had his legs underneath him from start to finish.

"First of all you don't feel the same," Olynyk said of playing at less than 100 percent. "You're not moving the same. You don't have the same push or the same power so your shot's a little bit off here and there. You're jumpy a little bit defensively. You kinda gotta get back into the swing of things. Get back into that physical presence too because with that ankle, you're not moving for two weeks so it's kind of tough."

With the rookie 7-footer's help, the Celtics stretched a 69-65 lead at the end of the third quarter into an 85-74 advantage in the fourth.

Coach Brad Stevens -- who elected to play Olynyk, Kris Humphries and Gerald Wallace over Jeff Green, Brandon Bass and Jared Sullinger late in the game -- called Tuesday's loss Olynyk's best game as a pro.

"He got extended minutes, and we were playing well with him," Humphries said. "He shot the ball with confidence. He's a playmaker. He can pass. He's a really good all-around player. A lot of times it's just playing minutes, getting confidence and seeing things go your way."

Phil Perry serves as a general reporter for Comcast SportsNet, mainly covering the New England Patriots. Follow Phil on Twitter here.